Prior art timepieces generally have had the problem of requiring a complicated adjustment procedure to change over from the time complex for daylight-saving time to that for standard time. To simplify this procedure, an electronic digital clock, as shown from the EP-A-0 197 336, has a separate selector button by which the hour display can be adjusted by .+-.one hour. However, there is no indication whether the time displayed is for daylight-saving time or for standard time. Each time the selector button is pressed, the hour display is alternately switched ahead or back by one hour. A problem develops if the button is pressed twice by mistake. This has the effect of switching the display back to the original time complex. The use of separate luminous markings to display the currently selected time complex poses a problem as the timepieces usually only have very small displays and therefore cannot accommodate such an additional making.